Module Contact: Dr Beatriz de la Iglesia, CMP Copyright of the University of East Anglia Version 1

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1 UNIVERSITY OF EAST ANGLIA School of Computing Sciences Main Series UG Examination DATABASE SYSTEMS CMP-4010B / CMP-5038B Time allowed: 3 hours Answer THREE questions out of FIVE. All questions carry equal weight. Notes are not permitted in this examination Do not turn over until you are told to do so by the invigilator. CMP-4010B / CMP-5038B Module Contact: Dr Beatriz de la Iglesia, CMP Copyright of the University of East Anglia Version 1

2 Page 2 1. a) In the context of the relational data model give a brief definition of the following concepts: i) entity integrity. ii) iii) referential integrity. domain integrity (12 marks, 4 marks each) b) The following tables form part of a database held in a relational DBMS: Student (studentid, lastname, firstname, address, phone) Module (moduleid, description, prerequisiteid) TimetableEntry (moduleid, day, hour) Enrolment (studentid, moduleid, year, mark) i) Identify suitable candidate keys and a primary key in each table, stating any assumptions you need to make. ii) Identify any foreign keys for each table in the schema. (4 marks) iii) Explain how the entity and referential integrity rules may apply to these tables. (14 marks) Total (40 marks) CMP/4010B / CMP-5038B Version 1

3 Page 3 2. A library has a relational database containing information on people, books and loans of books to people. The tables are: Book (bid, title, author) Person (pid, name, owed) Loan (bid, pid, due) where bid is book identifier number, pid is the person identifier, owed is the amount owed in library fines and due is the data a loaned book is due to be returned. For simplicity, it is assumed that each book has only one author. Formulate SQL statements to meet the following requirements: a) Produce a list of all books in author sequence; where an author appears more than once, his/her books should be in title order. b) Produce a list of all books with the word management in the title. c) Produce a list of names of persons with books on loan which must be returned by 1 st August (4 marks) d) Given a specific person s name, produce a list of the titles of the books he/she has on loan in due date order. (5 marks) e) Produce a list of all books with "Database" in the title and, if they are out on loan, the date they are due to be returned. (5 marks) f) Calculate the total amount of fines owed. g) For each person with books on loan, list their name, and how many books they have on loan. Those without books on loan should also be included with a count of 0. (4 marks) h) Given a person s name, reset the amount they owe in fines to zero. i) Insert a new book Database Systems by C. J. Date. The book identifier should be one greater than the largest book identifier in use. j) Produce a DDL SQL statement to create the loan relation. The table definition should contain named primary key and foreign key constraints. It should also enforce the following referential integrity constraints: (i) a book cannot be deleted if it is on loan and (ii) a person cannot be deleted if he/she has books on loan. You can assume that when books are returned they disappear from the loan relation, hence the only books in the loan table are those which are still due. Add a check constraint to ensure that the due date is always greater than the current date. (7 marks) PLEASE TURN OVER Total (40 marks) CMP-4010B / CMP-5038B Version 1

4 Page 4 3. The question requires you to write some code. Minor syntactic errors will not be penalized. a) Python, Psycopg2, Flask and PostgreSQL are components that can be used to construct a web based system. Describe the function of each of these components within the system. b) Write the body of an HTML page to allow a user to enter an ID and name onto an HTML form and submit it to a Python function. c) Write a Python function to accept an ID and name from an HTML form and add it to a database. Assume the following: - the database is hosted at db.cmp.uea.ac.uk and it is called mydb ; - the user is user ; - the password is password ; - the database has a schema called name_data ; - the schema has a single table called names comprising two columns: ID and last_name. (20 marks) Total (40 marks) CMP/4010B / CMP-5038B Version 1

5 Page 5 4. An e-commerce database has a customer table containing 32,000 entries. It is defined as follows: create table customer ( forename char (20) NOT NULL, surname char (24) NOT NULL, char (40) NOT NULL, last_logon date NOT NULL); The column is unique. The date datatype is 16 bytes. The page size is 2048 bytes, a disk address is 8 bytes and no allowance is made for housekeeping information in rows or on pages. B-tree pages are no more than 70% full when they are created. Two possible queries are: (i) given a unique , find the surname; (ii) given the leading fragment of an , find the surname and forename Assume that, on average, an fragment matches 100 customers. a) Assuming customer is a heap file, estimate the number of I/O operations needed to answer each query. (8 marks) b) Assuming the customer table is a B-tree with as the key, how many levels of index are needed? Estimate the number of I/O operations needed to answer each query. (16 marks) c) Assuming a secondary index is built on surname and that this is also a B-tree, how many levels of index are needed? How many I/O operations are needed, on average, to find the and last logon of a customer given a surname? Assume that there are, on average, 100 duplicates of the surname. (16 marks) (Total 40 marks) PLEASE TURN OVER CMP-4010B / CMP-5038B Version 1

6 Page 6 5. A property maintenance company wants to put their data into a database in order to introduce an order processing system. The analysis of requirements leads to the discovery of the following two tables where information is currently stored: Job job_no date cust_no task_no task_desc est_hours est_price J123 10/4/14 C300 L0001 Mow Lawn G0303 Clear Gutters 1 15 H0004 Trim Hedges 1 20 J124 12/4/14 C103 G0303 Clear Gutters P0033 Paint Door J125 17/4/14 C300 L0001 Mow Lawn 1 20 G0303 Clear Gutters Customer cust_no cust_name address engineer engineer_name C103 Trevor Jones 3 High Street E6640 Rick Sparks Epsworth C300 Carl Smith 12 Farbank E4759 Jack Hammer Wessex C320 Hannah King March House E6640 Rick Sparks Coverington C323 Joe Parker 6 The Rise Cohenton E3941 Mary Jupp Assume that each customer is allocated to an engineer. Also assume that the estimated hours and estimated price depend both on the job and the task. a) Convert the above tables to first normal form (1NF) and identify primary keys in the resulting 1NF tables. b) Draw up a list of functional dependencies for the 1NF defined data and thus convert the relation definitions into second normal form (2NF) and then to third normal form (3NF). Explain the process you follow. (21 marks) c) How is Boyce-Codd Normal Form (BCNF) different to Third Normal Form (3NF)? Are the relations you obtained in b) after normalization to 3NF in BCNF? (9 marks) Total (40 marks) END OF PAPER CMP/4010B / CMP-5038B Version 1